1. Technical Field
The present invention relates to a nozzle plate having a nozzle opening to discharge liquid drops, and a liquid ejecting head and a liquid ejecting apparatus including the nozzle plate.
2. Related Art
In general, an ink jet type recording head known as a representative example of a liquid ejecting head includes a nozzle plate where a plurality of nozzle openings to discharge liquid drops are formed, and a passage forming substrate where a pressure generating chamber communicating with the nozzle opening is formed. In such liquid ejecting head, a silicon substrate is used in the passage forming substrate and the nozzle plate for an increase in nozzle density, and both thereof are bonded with each other by an adhesive agent.
JP-A-2009-184176 discloses a method for suppressing residual of the ink, in which a surface of a silicon nozzle plate bonded with the passage forming substrate and an inner surface of the nozzle opening are provided with a first ink-resistant protective film formed from an oxide silicon film by thermal oxidation, and a second ink-resistant protective film formed from metal oxide such as a tantalum pentoxide film formed by thermal CVD and plasma CVD and, further, a third ink-resistant protective film (base film) formed from metal oxide such as a tantalum pentoxide film formed by thermal CVD and plasma CVD and a liquid-repellent film (ink-repellent film) are formed on an ink discharge surface.
Also, JP-A-2004-351923 discloses a structure in which a base film such as a plasma-polymerized film of a silicone material and a liquid-repellent film disposed on the base film such as a metal alkoxide-polymerized molecular film are disposed as the liquid-repellent film of a nozzle discharge surface.
However, particularly in a case where the nozzle has high density, there is a case where a uniform film is unlikely to be formed on the inner surface of the nozzle opening, particularly up to the vicinity of the discharge surface, such that an ink resistance problem is likely to occur when the ink-resistant protective film formed of the metal oxide is disposed by CVD, and where film thickness is likely to be large and not uniform and a problem of non-uniformity of discharged ink drops arises when a sufficient film is to be formed over the entire surfaces. In a case where the above-described nozzle plate is a silicon nozzle plate in which a nozzle hole is formed on the silicon substrate by using anisotropic etching, there is a case where an adhesive property of the ink protective film causes a problem.
In addition, the base film such as the plasma-polymerized film of the silicone material of JP-A-2004-351923 has a possibility of generating microdefects, and there is a case where a problem such as peeling of the liquid-repellent film arises due to such microdefects.